1. Field of the Invention
The present invention relates to a cooling apparatus and, more particularly, to a cooling apparatus which cools a cooling target such as a substrate to be processed in a vacuum container, or a laser oscillator.
2. Description of the Related Art
To cool a cooling target such as a substrate to be processed in a vacuum container, or a laser oscillator using a refrigerating machine, usually, the cooling target is directly brought into tight contact with the cooling portion (made of a metal having high thermal conductivity) of a refrigerating machine.
When the cooling target is an object that should not be vibrated, the refrigerating machine is installed at a location away from the cooling target and a liquid refrigerant cooled by the refrigerating machine is supplied under pressure into a heat-insulated pipe using the power of a circulating pump or the like, thus cooling the cooling target.
This can cool the cooling target indirectly while reducing vibration from the refrigerating machine.
Japanese Patent Laid-Open No. 2000-146342 discloses a refrigerating apparatus in which a vibration-proofing means is arranged between a refrigerating machine main body and a cooling target portion in contact with the refrigerating machine main body, and the vibration-proofing means comprises a vibration-proofing rubber member and a plurality of spherical members.
As described above, in an atmosphere or vacuum, when cooling the cooling target by fixing it to the refrigerating machine cooling portion, vibration generated by operating of the refrigerating machine may undesirably be transmitted to the cooling target.
Therefore, the conventional refrigerating apparatus cannot be used for a cooling target that should not be vibrated.
When installing the refrigerating machine main body at a location away from the cooling target and cooling the cooling target indirectly with the refrigerant which is supplied under pressure using the power of a circulating pump or the like, the installation distance between the refrigerating machine main body and the cooling target must be large. Therefore, it is difficult to arrange the apparatus particularly in a vacuum container.
Hence, a heat-insulated long pipe is set in the atmosphere, and the refrigerant is supplied under pressure through the pipe. Even with the heat-insulated pipe, however, external heat largely influences the pipe, and the refrigerant temperature rises during supply under pressure, thus decreasing the heat transfer efficiency.
To forcibly supply the refrigerant under pressure, power from a circulating pump or the like is required. Heat generated by the motor or the like of the circulating pump may increase the refrigerant temperature.
With the technique described in Japanese Patent Laid-Open No. 2000-146342, when the cooling target is set in direct contact with the vacuum container to cool it integrally with the vacuum container, vibration may undesirably be transmitted from the refrigerating machine main body to the cooling target.